2011 Vol. 26, No. 2

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Experimental investigation of clocking effect in a compressor with positive bowed stator in different axial gaps
LU Hua-wei, CHE Cong-bin, ZHONG Jing-jun, GUO Shuang, CHEN Fu
2011, 26(2): 241-248.
Abstract PDF(1564KB) icon1916 icon16
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The clocking effect of a double stage compressor with positive bowed stator in different axial gaps between rotor and stator rows was investigated in this paper.The traverse flow field was measured in detail at the second stators outlet.The experimental results show that clocking effect changes little while the axial gap reduces.The diffusion ability intensifies while the input torque increases.The efficiency increases firstly and then decreases.It means that there is an optimal axial gap.At the same time,the surge margin decreases while the axial gap reduces.
Measurement of rotating stall in an axial compressor using a single slanted hot-wire probe
WANG Hong-wei, SONG Zhi-qiang, WANG Zhi
2011, 26(2): 249-254.
Abstract PDF(976KB) icon1831 icon13
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A method was developed to measure reversed flow using a single slanted hot-wire probe.Probe rotating technique was used to measure three-dimensional velocities with a single-sensor probe, and the wake of the prong was used to determine the direction of the flow.The method was applied to measure the rotating stall in a low speed axial compressor.The results give a detail view of the flow structure in the rotating stall cell, demonstrating that this technique is simple and accurate in the measurement of reversed flow.It is especially applicable in the measurement of three dimensional flow field within turbomachinery.
Three-dimensional unsteady model of effects of rotating inlet distortion on flow instability in compressor
TU Bao-feng, HU Jun
2011, 26(2): 255-261.
Abstract PDF(1560KB) icon1608 icon16
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Based on three-dimensional unsteady actuator disk model,a three-dimensional compressible unsteady model was developed to predict the stall inception and the effects of inlet distortion on performance and aerodynamic stability of compressor,and the effects of amplitude and frequency of rotating distortion on the performance and aerodynamic stability of a two-stage low-speed axial compressor were analyzed using this model.The results show that both of the distortion amplitude and rotating frequency will affect the stall boundary and stall inception strongly.The worst situation is that the rotating frequency equals to the stall cell.The rotating distortion will not affect the positions where the stall cell firstly appears,and the tip region of the compressor always comes into the stall cell firstly.The comparison of the simulation and experiment results shows that the model is reliable.
Numerical research on enhancing the axial compressor performance by bleeding
ZHAO Bin, LI Shao-bin, LI Qiu-shi, ZHOU Sheng
2011, 26(2): 262-271.
Abstract PDF(1404KB) icon2150 icon17
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By analyzing the low-speed single-stage compressor,six different bleeding plans were presented according to their influence mechanism on the compressor performance.A numerical simulation was conducted to study the influence of bleeding on the compressors total pressure rise and stability margin.The results show that,for the stators with large flow separation in the corner,it is better to bleed air both from the suction surface of the casing and the blade suction surface near the hub simultaneously,so as to improve total pressure rise and stability margin with a small amount of bleed air.The conclusion steadily supports a concept that it is very necessary to combine air system bleeding with the compressor flow control during engine performance study.
Aerodynamic design and numerical simulation of a highly loaded transonic two-stage fan
JIN Hai-liang, JIN Dong-hai, GUI Xing-min
2011, 26(2): 272-280.
Abstract PDF(1313KB) icon2063 icon27
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The design procedure and result of a highly loaded transonic two-stage fan for a variable cycle engine were presented.The selection of key parameters was discussed during the design procedure.The throughflow calculation and blade design were completed using the S2m streamsurface-based streamline curvature method and arbitrary camber lines blading method.The design strategies of swept rotors and stators were adopted to improve the efficiency and stall margin of the fan.Three-dimensional computation results indicate that the design targets of the two-stage fan are achieved except for the adiabatic efficiency.The fan has relatively high peak efficiencies above 80% rotating speed.
Experimental investigation of airfoil-wake interaction of wind turbines using PIV
LI Mao-yi, YUAN Wei, LI Zhi-ping, GAI Feng, LU Ya-jun
2011, 26(2): 281-288.
Abstract PDF(1745KB) icon1591 icon21
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The airfoil-wake aerodynamic interaction of wind turbines was experimentally investigated using PIV(particle image velocimetry) technology.It analyzed the flow structure of downstream airfoil when the wake excited the leading edge,suction side and pressure side of airfoil,respectively.The results indicate that the helpful wake excitation is unsteady excitation which doesnt change main flow of downstream airfoil distinctly.The separation area at the suction side is restrained under the wake excitation at leading edge of airfoil when the upstream and downstream airfoils have the same incidence angle and appropriate axial-spacing.
Study of loss mechanism in low speed compressor cascade using dissipation function
LIU Hua-ping, CHEN Huan-long, YANG Xiao-guang, CHEN Fu
2011, 26(2): 289-296.
Abstract PDF(1606KB) icon2020 icon17
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The transport equation of total pressure containing dissipation function was derived.Through experimental and numerical studies of a low speed compressor cascade,the characteristics of flow and loss distribution were discussed in detail,then the loss mechanism was obtained.The results show that:the high cascade loss originates from dissipation in the area near the blade leading edge,blade and end wall surface,wakes,as well as the area between the separation and mainstream.Moreover,the separation zone is only a low-energy fluid gathering area for large total pressure loss and entropy rather than a zone of loss source.The essences of improving the cascade performance by controlling separation are weakening the shear strength and reducing the strong shear zone in the area between the separation and mainstream by increasing the velocity and reducing separation area.A method of improving the cascade performance by controlling the evolution of boundary layer and horseshoe vortex at the cascade inlet is recommended.This paper presents a new thought of controlling cascade losses.
Aerodynamic performance investigation of a compact compression system for turbofan engine
QUE Xiao-bin, HOU An-ping, ZHOU Sheng
2011, 26(2): 297-303.
Abstract PDF(1164KB) icon1731 icon16
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The performance of a compact compression system with fan-bypass-core compressor configuration was investigated numerically in this paper.The throttling methodology for accessing performance of fan-bypass-core compression system and its implementation during the numerical simulation was discussed.The calculated design speed performance of fan and high pressure compressor (HPC) shows that the design targets are achieved for mass flow,total pressure ratio and efficiency,while the stall margin of fan is only 7.8%,lower than the required value.Analysis of the flow field evolution shows that,during core nozzle throttling,the system instability is initiated in the exit stage of HPC;during bypass nozzle throttling,however,the large extent blockage,which is caused by the interaction of rotor tip vortex and passage shock,may contribute to the instability of the compression system.
Investigation on six-tube aero-valve PDE with coordinate operation
LIU Hong, TANG Hao, WANG Zheng-wei, LI Jian-zhong, WANG Jia-hua, ZHANG Jing-zhou
2011, 26(2): 304-309.
Abstract PDF(1035KB) icon1824 icon24
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In order to obtain the coordinate operation with six-tube aero-valve pulse detonation engine(PDE),ion sensor technique was mainly used to study the experiment under common air inlet conditions.At the same time,propagation velocity of combustion wave behind shock wave was measured quantitatively and the experiment was also validated with a pressure sensor.According to the results,the six-tube PDE can work coordinately and continuously at the operation frequency of single pipe 30Hz(the total operation frequency 90Hz).Besides,all detonation tubes reached the speed of detonation wave when the local evaporator was employed to improve the fuel evaporation.
Correction the relatively amount of kinetic energy of straight through labyrinth seal based on the wall jet theory
JI Guo-jian, JI Hong-hu, WANG Zheng-wei
2011, 26(2): 310-314.
Abstract PDF(915KB) icon1947 icon14
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Based on the analysis and summary the some leakage calculation methods characteristics and flow process on the straight through labyrinth seals,the relatively amount of kinetic energy being carried from throttling into the next was considered by use of the theory of two-dimensional (2-D) wall jet and compared with the Vermes method and numerical simulation.The result is that the jet flow in labyrinth cavities has the similar basic characteristics of two-dimensional wall jet flow such as the self-similar distribution of mainstream velocity;an empirical formula developed based on the 2-D wall jet theory is better than that based on the free jet theory and little higher than numerical simulation.
Study on cyclic variations of combustion in mini two-stroke aviation engine
LI Bing-lin, WEI Min-xiang
2011, 26(2): 315-322.
Abstract PDF(1199KB) icon1643 icon18
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The maximum pressure,maximum rate of pressure rise,mass fraction burn and its corresponding crank angle and reconstruction phase space were used to evaluate the cyclic variations of cylinder pressure under different working conditions of two-stroke aviation gasoline engine.On a comparative basis,the method of mass fraction burn and its corresponding crank angle can indicate the cyclic variations of engine more effectively.For the problem of cyclic variations of engine working in medium speed and different loads,the results show that cyclic variations will decrease with load increase,because the decrease of asymmetry of mixture gas is a main factor.After analyzing the cyclic variations at high speed working,the mini two-stroke aviation gasoline engine can work in normal condition because its coefficient of variation at different working conditions is less than 10%.The paper provided a contrastive method for performance analysis of combustion after the fuel was changed from gasoline to aviation kerosene.
Numerical simulation of ice accretion on airfoils
YANG Sheng-hua, LIN Gui-ping
2011, 26(2): 323-330.
Abstract PDF(1285KB) icon2024 icon22
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To predict ice shapes on airfoils,a methodology for time-stepping ice accretion simulation was created.A software framework was developed to realize automatic ice accretion calculation and mesh updating process.The ice accretion thermodynamic model was built on Messingers conservation equations for mass and energy.The convective heat transfer coefficient was computed based on an extension of the Spalart-Allmaras turbulence model on rough wall.A new ice growth method was proposed.Test cases show that the present method is capable of simulating long-time rime,glaze ice accretion and the cases with two complex ice horns.Comparison with the experimental ice shape data of a NACA 0012 airfoil shows that the computed results are satisfactory.
Experimental investigation of cooling effectiveness of spiculate lamilloy
ZHANG Bin, ZHU Hui-ren, CAI Yi, XU Du-chun
2011, 26(2): 331-336.
Abstract PDF(943KB) icon1747 icon15
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Five true scale spiculate lamilloys were studied to analyze the cooling effectiveness based on the former inner surfaces heat transfer characteristics,and an experiment was tested in a large-scale,low-speed close-looped wind tunnel.The result shows that very high cooling effectiveness can be achieved by using spiculate lamilloy.The ratio of hole pitch to impingement hole diameter(S/D) and the diameter of film hole (Dout) play important roles in determining the cooling effectiveness,the smaller S/D or larger Dout means higher cooling effectiveness.The pin diameter (Dpin) has little influence on cooling effectiveness.When blowing ratio is constant,the gas velocity also has little influence on cooling effectiveness,while blowing ratio is a major influential factor to film cooling effectiveness.
Experimental study of evaporation rate for multihole vaporizer with pressure swirl atomizer
GUANG Hui, XU Quan-hong, ZHU Jing, LIN Yu-zhen
2011, 26(2): 337-342.
Abstract PDF(931KB) icon1723 icon20
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A design multihole vaporizer was developed for micro gas turbine combustor.Pressure swirl atomizer was used to atomize kerosene first and was fitted at entrance of multihole vaporizer.A lap of holes were distributed around multihole vaporizer wall of nozzle downstream,which were used to mix and vaporize kerosene.Spray characteristics of pressure swirl atomizer was measured,and vaporization rate of the multihole vaporizer was studied experimentally.The experimental results show that the air temperature and spray characteristics of pressure swirl atomizer are major influence factor to vaporization rate for multihole vaporizer.Kerosene is completely vaporized when the vaporizer inlet temperature exceeds 480K.The smaller the kerosene particle size,the greater relative velocity,the higher the level of evaporation achieved.
Effects of sheltering baffles on the infrared radiation characteristics of two-dimensional nozzles
FANG Ren-yu, ZHANG Jing-zhou, SHAN Yong
2011, 26(2): 343-348.
Abstract PDF(1233KB) icon2176 icon23
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The non-axis-symmetric circular-to-rectangular nozzle is capable of suppressing the infrared radiation signature with less performance loss compared to axis-symmetric nozzle.This paper researched the effects of different sheltering baffle structures on the infrared radiation suppression of the two-dimensional nozzle with aspect ratio 3.33 by computational fluid dynamics/infrared radiation (CFD/IR) numerical simulation.The investigation shows that the double-sheltering baffles with film slots on the upper sheltering baffle have more obvious infrared radiation suppression effect.
Conjugate heat transfer investigation on a gas turbine blade
HU Jie, LIU Jian-jun, JIANG You-dian
2011, 26(2): 349-354.
Abstract PDF(1006KB) icon1746 icon18
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This paper described the conjugate heat transfer (CHT) investigation on the Mark Ⅱ blade with hot-gas test data.The CFX solver was used for CHT and non-CHT simulations,and the corresponding results were analyzed and compared in detail.The results show that,even if the correct averaged temperature is specified on the blade surface,the calculated heat transfer coefficient distributions by using non-CHT method still exhibit some deviations due to the non-coupled boundary conditions,as compared with the CHT method and experimental data.The present investigation reveals the necessity and accuracy of CHT method.
Study on high cycle fatigue fractal damage model of TC11 alloy welded joint
LIU Xiao-gang, GUO Hai-ding, WANG Bang-zhong, LI Jin-wei, WU Bing
2011, 26(2): 355-361.
Abstract PDF(1166KB) icon1688 icon18
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Based on the fractal characteristic of the metal fatigue fracture surface, Chaboches high-cycle fatigue (HCF) damage model was extended to fractional dimension space.An HCF fractal damage evolution model considering internal micro damage mechanism was built up in the present paper.By the stress-controlled test,HCF properties of TC11 alloy welded joint were measured;and fractal dimension of the fracture surface was calculated through its scan electron microscope (SEM) picture.The key parameters of damage evolution model mentioned above were obtained through experimental data fitting,and fractal damage evolution equation of TC11 alloy welded joint under each loading level was found thereof.
High cycle fatigue life experiment of sheet metal with coldworking hole
YANG Xing-yu, MENG Xiang-ming, DONG Li-wei, DUAN Jia-kuan, GENG Zhong-xing, ZHAO Fu-xing
2011, 26(2): 362-369.
Abstract PDF(1217KB) icon1756 icon14
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In order to enhance the fatigue strength of the pressure equalizing hole on labyrinth seal disc for a compressor,three kinds of coldworking techniques with different processes have been designed, i. e .:one-sided multiple extrusion process,cylindrical extrusion process and T shape extrusion process.High cycle fatigue tests of sheet metal specimen made of two kinds of materials with hole were conducted under room temperature and high temperature in three different processes.Test results indicate that sheet metal with coldworking hole produced in T shape extrusion process can efficiently enhance the fatigue strength.
Integral data fusion method for multigroup type-Ⅱ censored tests under the same condition
LIN Feng-chun, KANG Rui
2011, 26(2): 370-375.
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An integral data fusion method for multigroup type-Ⅱ censored tests under the same condition was presented for normal distribution,lognormal distribution,extreme value distribution,Weibull distribution and other location-scale distributions.This method could integrally infer censored data in multiple groups under the same conditions,and give the integral fusion estimate of the location and the scale parameter.And then,the estimator and the confidence interval of population percentile were established.Compared with traditional methods,the presented method not only has higher precision but also solves the problem of reliability assessment with very small sample.
Structural optimization of hollow fan blade based on orthogonal experimental design
YANG Jian-qiu, WANG Yan-rong
2011, 26(2): 376-384.
Abstract PDF(1111KB) icon1819 icon24
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Several structural optimization parameters for the description of the geometric features of a hollow fan blade were determined,then a finite element model was established for the parameterized hollow fan blade.And,a method was developed for automatically updating high-quality finite element grid in hollow fan blade in the iterative process of design optimization.Based on the discrete design parameters already simplified and assumed,the structural design optimization problem for a hollow fan blade based on strength constraint and minimum mass was converted into a multi-objective optimization problem without constraints.Finally,the Pareto optimal solutions were found by numerical orthogonal experimental design method in a several turn.
Application of cyclic symmetry property in transient forced vibration of bladed disks
YAO Jian-yao, WANG Jian-jun
2011, 26(2): 385-391.
Abstract PDF(1122KB) icon1805 icon17
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A method for transient response calculation of bladed disks was presented using the cyclic symmetry property of the structure.The stiffness and mass matrices of expanded sector were generated by ANSYS.The transformation matrix from expanded sector to basic sector was obtained using the corresponding nodes on sector boundaries.The load vector for the cyclic symmetric model was obtained from the spatial Fourier transformation of the forces on every sector.The transient responses were calculated using Newmark method,and multi-frontal method was selected as the direct equation solver.A bladed disk with 12 sectors was applied as the numerical example,indicating that the proposed method is effective for transient analysis of bladed disks.
Prediction method of blade flutter boundary in a compressor stage
ZHANG Xiao-wei, WANG Yan-rong, XU Ke-ning
2011, 26(2): 392-396.
Abstract PDF(997KB) icon1918 icon25
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The blade flutter boundary in a compressor stage was obtained by the developed numerical prediction method based on the energy method.The displacements of blade surface structural nodes,obtained from the computational structural dynamics (CSD) analysis,were transferred to fluid interface grids,and the designed multi-layer moving grid technique was applied to computational fluid dynamics (CFD).The unsteady analysis under the oscillating cascades was achieved to calculate the unsteady aerodynamic work for aerodynamic modal damping ratio.For a certain first-stage compressor rotor,the aeroelastic stability of different operating conditions was investigated and compared at different blade modes.And the blade flutter boundary has been obtained by analyzing the distribution of aerodynamic modal damping ratio in compressor characteristic map.The results show that the developed numerical method for aerodynamic modal damping ratio to determine the flutter boundary is feasible to preliminarily predict the aeroelastic stability of compressor blade.
Analysis on dynamic characteristics of high speed cylindrical roller bearing
ZHANG Zhan-li, WANG Yan-shuang, DENG Si-er, LIU Zhe
2011, 26(2): 397-403.
Abstract PDF(1154KB) icon1699 icon34
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A nonlinear dynamic mathematical model of high speed cylindrical roller bearing was presented.Newton-Raphson method was used to solve the model,and the dynamic performance parameters of roller bearing were obtained.Under different radial loads,the variations of the rollers rotational speeds were discussed.The distributions of minimum oil-film thicknesses and contact loads between rollers and raceways were obtained.The results show that the number of loaded rollers increases with the increasing radial load at certain speed,and smaller radial load could lead to serious slippage and lower rotational speeds of rollers in loading region.The minimum oil-film thickness between each roller and inner raceway is thinner than that between each roller and outer raceway in loading region.By comparing with the results of a calculation example of large-scale analysis software “SHABERTH” and verification test,it shows that the analysis method on dynamic characteristics of high speed cylindrical roller bearing in this paper is not only accurate and reliable,but also simple and suitable to engineering applications.
Investigation on power loss of homopolar active magnetic bearing with zero-bias current control
XIE Zhen-yu, WU Kai-feng, SHI Qing-cai, HUANG Pei-zhen
2011, 26(2): 404-408.
Abstract PDF(1131KB) icon1750 icon22
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Homopolar radial active magnetic bearing (AMB) and axial zero-bias current control were introduced into the AMB system in this paper.Influence on power loss of AMB by the two methods was investigated by actual operation of the system.The results show that these two methods can reduce power loss of AMB effectively,and can also be applied to improve efficiency of aero engine as compared with heteropolar radial AMB and axial bias current control.
Tooth profile modification of helical gears and experimental study based on finite element contact analysis
WU Yong-jun, WANG Jian-jun, HAN Qin-kai, LI Qi-han
2011, 26(2): 409-415.
Abstract PDF(1212KB) icon1774 icon34
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The precise tooth profile modification (TPM) of helical gears based on finite element contact analysis has been investigated,and the vibration comparative experiment has been carried out for verification.An accurate finite element contact analysis model of helical gears was established directly under ANSYS,while the integrated elastic deformation of the meshed teeth was extracted directly from the finite element contact analysis results,and considered as the main basis of the amount of tooth profile modification;then the precise tooth profile modification was presented.According to the presented design of tooth profile modification,the comparative experiment system was built up,and the vibration comparative experiment was carried out under a variety of speed and load conditions;then the actual effects and characteristics of vibration and noise reduction of the modified gears were discussed.Researches show that,the presented precise tooth profile modification is quite correct and reasonable,and also has a good effect of noise and vibration reduction,with the biggest reduction under each criterion down to 11.28dB and 4.69dB .
Sealing performances analysis for a herringbone-grooved finger gas seal structure and working parameter
SHEN Xiao-long, CHEN Guo-ding, SU Hua
2011, 26(2): 416-421.
Abstract PDF(993KB) icon1785 icon18
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An analysis model of a herringbone-grooved finger gas seal system was presented for its structure and working parameter.The dynamic leakage and dynamic load capacity were subsequently calculated.With this model,analysis and calculation were performed with the change of different herringbone-grooved parameters and working conditions for the sealing performance of the seal.The calculated results indicate that the sealing performance is straightly affected by herringbone-grooved parameters.Rotor speed and windage have different influences on the leakage and load capacity.The above results are validated by comparing with the test data in references,thus providing a better basis for design of the seal.
Nominal limit state factor and dimension reduction method in reliability optimization for turbine disk
YANG Jun-jie, WANG Rong-qiao, FAN Jiang, SHEN Xiu-li
2011, 26(2): 422-427.
Abstract PDF(1129KB) icon1654 icon16
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Computing intensity and cost consuming are two important difficulties in reliability-based design optimization (RBDO).the single-looping optimization (SLO) methods and the double-looping optimization (DLO) methods cannot deal with them.Some based on the inverse most probable point (MPP) transforms the probabilistic constraints to deterministic constraints,but they cannot decouple the two procedures including reliability analysis and optimization,in additional,there are too large errors because of using the first order reliability methods(FORM) in the methods to be adaptive in aero-engine design.The nominal limit state factor method was proposed that can decouple the two procedures of reliability analysis and optimization and can make the reliability analysis become a pre-procedure before optimization.Moreover,the uni-variate dimension reduction method was used to obtain accurate probability of failure that only requires the results of FORM in previous reliability analysis.Finally,an example on structure optimization for turbine disk was given to illustrate that the proposed methods are more efficient than the DLP method and are close to the deterministic optimization in efficiency.
Parametric model and design of full flow staged combustion cycle engine system for (Ⅰ) engine balance characteristics
JIN Ping, LI Mao, WANG Xiao-wei, LI Jia-wen, CAI Guo-biao
2011, 26(2): 428-434.
Abstract PDF(1055KB) icon1832 icon38
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The full flow staged combustion (FFSC) cycle engine balance model was established and the pressure relationship between the fuel-rich flow and the oxygen-rich flow was added in this model.These results show that (1) mixture ratios of preburners are matched for each other,mixture ratio of ox-rich preburner decreases with increasing mixture ratio of fuel-rich preburner,helping to balance the work of two side preburner gases;(2) with the increase of mixture ratio of fuel-rich preburner,the preburner gas temperature is enhanced,the fuel-rich preburner gas mass flowrate is enlarged (the ox-rich preburner gas mass flowrate reduced),the working ability of preburner gas is reinforced,and the fuel pump lift falls down(the oxidizer pump lift ascends);(3) the mixture ratio of preburner determines the preburner gas temperature,influences the preburner gas properties,participates in the mass flow distribution,controls the working ability of preburner gas,and then affects the pump lift.
Parametric model and design of full flow staged combustion cycle engine system for (Ⅱ) parameterization design
JIN Ping, LI Mao, WANG Xiao-wei, LI Jia-wen, CAI Guo-biao
2011, 26(2): 435-441.
Abstract PDF(965KB) icon1902 icon55
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Based on the full flow staged combustion (FFSC) cycle engine balance model,three parameters were selected for the engine system design,such as hydrogen transpiration cooling mass flow rate,combustion chamber pressure and combustion chamber mixture ratio.These results show that,when the thrust and nozzle expansion ratio are kept constant:(1) with the increase of hydrogen transpiration cooling mass flow rate,the fuel pump lift ascends rapidly and the oxidizer pump lift falls down;(2) with the increase of combusion chamber pressure,the pump lift ascends linearly before combustion chamber pressure at 20MPa and rapidly after 20MPa,so 20MPa is recommended for combustion chamber pressure;(3) with the increase of combustion chamber mixture ratio,the fuel pump lift ascends linearly,the oxidizer pump lift reduces rapidly and then slowly,so seven is recommended for combustion chamber mixture ratio.The effects of these design parameters on engine system parameters offer a reasonable range for engine system design.
Analysis of thermo-structure for attitude liquid rocket engine in ground test
HU Hai-feng, BAO Fu-ting, CAI Qiang, LIU Yang
2011, 26(2): 442-447.
Abstract PDF(1039KB) icon1830 icon21
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A research on the attitude liquid rocket engine using the film cooling and radiation cooling methods was performed.A model based on film cooling heat transfer,which employs an integrated analysis method,was presented by this paper.The finite element method (FEM) was used for coupling analysis of the thermal and structure of thruster chamber under the condition of calculated wall temperature and pressure distributions.At last,with use of the FEM,the thruster chamber buckling was discussed under the condition of the given temperature,pressure and the load of external pressure.The result was close to the referenced experiment result,with the greatest temperature error of 3.67%.The result indicates that the integrated analysis method for the simulation of heat transfer is efficient;taking into account of the thermal load,the buckling load is increased about 5.7933% than that without thermal load.The results provide some theory support for engineering applications.
Analysis on flow field of inner bore clapboard pulse solid rocket motor
CAO Xi-wei, LIU Yu, REN Jun-xue, WANG Yi-bai
2011, 26(2): 448-452.
Abstract PDF(968KB) icon1867 icon19
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In order to obtain the characteristics of the flow field of inner bore clapboard pulse solid rocket motor,the numerical simulation of flow field was carried out using the CFD (computational fluid dynamics) software based on the principle of the motor.On the condition of pure gas phase and gas-particle phase,the results were analyzed in terms of pressure,Mach number and temperature.Through the analysis,the characteristic of inner bore clapboard pulse solid rocket motors flow field was summarized.The pressure distribution was similar,but the Mach number and temperature contours had lag phenomenon.In addition,the solid particles had a severe effect on the wall of the nozzle expanding section.The result provides references for the design of the inner bore clapboard pulse solid rocket motor.
Numerical simulation of interaction unsteady flows around co-axial rotors in hover
XU He-yong, YE Zheng-yin
2011, 26(2): 453-457.
Abstract PDF(1188KB) icon1725 icon29
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Numerical simulation of three-dimensional(3-D)unsteady Euler equations was conducted to investigate the unsteady flows around co-axial rotors in hover.The thrust performances of two rotors became worse because of the interaction between them,and the influence of the upper rotor on the lower rotor was greater than that of the lower rotor on the upper rotor.The downwash velocity at the lower rotor plane was much larger than that at an isolated rotor plane,and the downwash velocity at the upper rotor plane was a little larger than that at an isolated rotor plane.The downwash velocity and thrust coefficient became larger when the collective angle of blades was added.With the increase of distance between the two co-axial rotors,the thrust coefficient of the upper rotor increased,and the total thrust coefficient reduced,because the thrust coefficient of the lower rotor dropped greater than the increment of the upper rotor.
Aerodynamic characteristics research on variable geometry inlet of combined cycle engine
YAN Hong-ming, ZHONG Jing-jun, YANG Ling, HAN Ji-ang
2011, 26(2): 458-467.
Abstract PDF(1262KB) icon1829 icon23
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To enable the flight of turbo/ramjet combined cycle engine within extensive altitude and speed,the aerodynamic structure of a variable geometry inlet for combined cycle engine was designed in this paper.Estimation program of shock structure with viscous correction was compiled to estimate the shock structures and intensities in the inlet under different Mach numbers and attack angles.The choice of the variable panel length was governed by the program.Considering the boundary layer suction,two-dimensional flow fields of the inlet were simulated from Mach number 1.6 to 4.0 at attack angles of -2°,0°,+2°.The structures of the flow fields were consistent with the computed results by the compiled program.Aerodynamic characteristics of the variable geometry inlet were acquired.The influences of Mach numbers and attack angles on the adjustment rules and aerodynamic characteristics of the inlet were analyzed.
Mathematical model for calculating wing download of tiltrotor aircraft
CAO Yun-yun, CHEN Ren-liang
2011, 26(2): 468-474.
Abstract PDF(1149KB) icon1764 icon32
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A mathematical model for calculating wing download of tiltrotor aircraft in helicopter mode,which covers hover and low-speed forward flight,was given according to the aerodynamic interaction effect of the rotor downwash flow on the wing.The rotor and wing interaction area model considered the tiltrotor aircraft geometry scale,the tilt angle of the nacelle and the flight condition as key elements.Then the model was integrated into the XV-15 tiltrotor aircraft flight dynamic model.The trim results show that the rotor and the wing interaction download model of tiltrotor aircraft is reasonable and effective.The wing download math model is suitable for tiltrotor aircraft flight dynamic mathematical model.
Control law and fault-tolerant control for turbo-shaft engine digital control system
YAO Hua
2011, 26(2): 475-480.
Abstract PDF(966KB) icon2167 icon15
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Mathematical model for a turbo-shaft engine and actuator was developed by using Simulink simulation tools in this thesis.Control laws for turbo-shaft engine control system,such as steady-state,acceleration and deceleration,fault-tolerant for key sensor failure found out afterward,were studied in simulation.It presented a full solution scheme of turbo-shaft engine control.Simulation results show that,the solution scheme can assure control system works steadily and has better steady-state and dynamic performance features,where there is fault or not.

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